In a wireless network, a wireless communication device (e.g., a Mobile Station (MS) or User Equipment (UE)) communicates with one or more radio access nodes to send and/or receive information, such as voice traffic, data traffic, and control signals. In some cases, the radio access node initiates sending information to the wireless communication device via a page request. As an example, the radio access node sends a page request to a wireless communication device in an idle or dormant state to trigger a corresponding page response from the wireless communication device and thereby acquire knowledge of its precise location as required to initiate setting up a traffic channel for sending information to the wireless communication device.
The radio access node sends the page request over a paging channel. The wireless communication device monitors the paging channel periodically based on its paging cycle. If the wireless communication device uses a legacy paging cycle, the wireless communication device wakes up approximately every few seconds to monitor its nominal paging block. If the wireless communication device uses a long paging cycle, the wireless communication device wakes up less often (e.g., on the order of days or weeks) to monitor its nominal paging block. While using the long paging cycle conserves power, undesirable delays can occur if the wireless communication device misses a page request and has to wait until the next paging cycle (e.g., days or weeks) to receive the missed page request.
As an example of a legacy paging cycle, a GSM case is considered wherein a number of parameters allow for determining how frequently a wireless communication device wakes up to read paging messages (i.e., the paging cycle) and which radio block in particular a wireless communication device will read within the context of a given paging cycle (i.e., the wireless communication device's paging group). For example, consider the case where the Total Number of radio blocks per 51-multiframe=10, where a Broadcast Control Channel (BCCH) uses 1 radio block per 51-multiframe. Assuming BCCH-Extended is not used, this leaves 9 radio blocks per 51-multiframe for the Paging Channel (PCH)+the Access Grant Channel (AGCH). Base Station Access Grant Blocks Reserved (BS_AG_BLKS_RES) determines how many radio blocks are reserved for AGCH (range from 0 to 7). This means the number of paging blocks per 51-multiframe=9−BS_AG_BLKS_RES (range from 9 to 2). Base Station Paging Periodicity in Multiframes (BS_PA_MFRMS) indicates the periodicity for transmission of PAGING REQUEST messages to the same paging subgroup and it ranges from 2 to 9. The “available” paging blocks per Common Control Channel (CCCH) are then those “available” per 51-multiframe on that CCCH multiplied by BS_PA_MFRMS (range from 2 to 9)=N. The number of different paging subchannels on the CCCH=(9−BS-AG-BLKSRES)*BS-PA-MFRMS (i.e., N ranges from 4 to 81). Base Station Common Control Channels (BS_CC_CHANS) is the number of common control channels in a cell (range 1 to 4). Common Control Channel Group (CCCH_GROUP) (0 . . . BS_CC_CHANS-1)=((IMSI mod 1000) mod (BS_CC_CHANS×N)) div N=Paging Channel. PAGING_GROUP (0 . . . N−1)=((IMSI mod 1000) mod (BS_CC_CHANS×N)) mod N=Paging Group. Paging group is simply the paging block a wireless communication device reads on its assigned CCCH once every BS_PA_MFRMS 51-multiframes. Wireless communication devices are therefore required to monitor every Nth block of their paging channel, where N equals the number of available blocks in total on the paging channel of the specific CCCH which their CCCH_GROUP is required to monitor. Which of these N blocks a wireless communication device monitors is determined by the PAGING_GROUP calculation above, and all the wireless communication devices listening to a particular paging block in the set of N blocks in total are defined as being in the same PAGING_GROUP. A wireless communication device that follows this procedure can be said to use the legacy paging procedure. A wireless communication device that uses a monitoring interval that is longer than stated by the parameter BS-PA-MFRMS can be said to use a long paging cycle.
One major factor that can limit the stand-by time of a wireless communication device is the device's paging cycle. The paging cycle refers to the frequency that the device needs to wake up and monitor a paging channel for page requests. Existing specifications assume that paging is time critical. As a result, a core network node operating in accordance with existing specifications will initiate paging as soon as possible after receiving an incoming user plane payload so that the payload can be delivered to the corresponding device as soon as possible. This approach requires a wireless communication device to spend a significant amount of energy monitoring the paging channel in case a page request is intended for that device. Often times, however, the page requests being monitored turn out to be intended for different devices. In addition, frequent monitoring of the paging channel might not be necessary for less time critical applications, such as certain machine type communication (MTC) applications. To conserve energy, devices running less time critical applications can use a long paging cycle. When using a long paging cycle, a device wakes up to monitor the paging channel less frequently than when a legacy paging cycle is used.
If a device uses a longer paging cycle (i.e., reduces the frequency of monitoring paging blocks), the penalty for missing one paging block (e.g., decoding failure) is high. During such an event, the device relies on paging retransmissions initiated by the core network or the radio access network, including the option of blind retransmissions (i.e., not knowing if the device has responded). As the frequency of paging block monitoring decreases, the importance of the device successfully receiving its page requests during the monitored paging block tends to increase. Otherwise, a missed page will mean the device will not be able to receive a page until the next instance of its paging group. This can become problematic for an application that triggers the paging activity because the nominal paging notification delay will at least double. For example, the use of longer paging cycles creates an expectation of a worst case delay of the user plane payload for the affected devices (e.g., service plans and corresponding charging rates may be based on these worst case delays being satisfied). As such, allowing this worst case delay (e.g., 1 day) to double (to 2 days for this example) due to a missed page may become unacceptable even for a device that supports less time critical applications.